Preheat the oven to 350°F (180°C). Butter and flour your bundt cake pan.
In the bowl of an electric mixer, cream the butter and sugar until light and fluffy. Add the eggs, one at a time, and mix until fully incorporated. Add the vanilla, lemon juice and lemon zest and blend.
In a small bowl, whisk together the cake and all purpose flours, baking soda and salt. Add the flour mixture to the batter in two steps, alternating with the buttermilk, and ending with the last addition of flour. Mix until just incorporated, taking care not to over mix. Divide the batter into the bundt cake pan.
Bake for 20-25 minutes, until a toothpick inserted comes out clean and the cakes are golden brown. Let the cakes rest for about 5-10 minutes in the pan, then invert onto a wire rack.
While the cakes cool, make the glaze by whisking together the lemon juice, sugar and limoncello. If you wish, you could heat the glaze over low heat in a small sauce pan. Let it cool slightly before brushing over the bundt cakes.